The World Health Organization has identified the prevention of blindness as a priority area of interest, particularly in developing countries. W.H.O. defines prevention of blindness as "systematic community based efforts to eliminate the overburden of preventable and easily curable blindness," particularly that due to trachoma, xerophthalmia, onchocerciasis and cataract. The chief goal of this renewal proposal is the development of simple and useful techniques to deal with preventable and easily curable blindness, particularly trachoma and other visually disabling diseases, including herpes simplex eye infections and other eye conditions. The specific objectives proposed include: (1) Development and refinement of assessment methods for blindness in developing countries; (2) the improvement of means to prevent blindness from trachoma, particularly through the development of more effective chemotherapy; (3) description in other chlamydial diseases (particularly more effective chemotherapy; (3) description of other chlamydial diseases (particularly pneumonia) associated with endemic childhood trachoma; (4) determination of the extent of ocular chlamydial infection in industrialized and developing countries (Egypt and Tunisia); (5) determination of the prevalence of disabling complications and evaluation of techniques of limit herpes simplex infections of the eye; and (6) studies on other conditions such as recurrent corneal erosions.